This invention relates to a quick connect fitting for the exhaust gas recirculation (EGR) tube of an internal combustion engine.
For many years now emission controls for internal combustion engines have included an exhaust gas recirculation system. The purpose of this system is to inhibit the formation of oxides of nitrogen, NO.sub.x, that are produced at the high temperatures and pressures occurring during combustion. To reduce the high temperatures of combustion, and thus the NO.sub.x emissions, some of the relatively inert exhaust gasses are routed back into the intake mixture of fuel and air. The EGR system includes an EGR valve which regulates the amount of exhaust gasses introduced to the air/fuel mixture. Sometimes this valve has been threaded into a passage formed in the intake manifold.
Recently, engine manufacturers have produced intake manifolds made of polymeric material for the purpose of saving weight and cost. Due to the high temperatures of the exhaust gasses, it is unreasonable to install the EGR valve directly in the intake manifold. Instead, a typical EGR system for an engine with a polymeric intake manifold includes a "hot side" EGR tube running from the exhaust manifold to the EGR valve, and a "cold side" EGR tube running from the EGR valve to the intake manifold. The hot side tube is attached to the exhaust manifold and EGR valve with a threaded fitting utilizing a metal-to-metal flange seal due to the extreme temperatures encountered. The cold side tube is also attached to the EGR valve with a threaded fastener. At the intake manifold the connection needs to insulate the polymeric intake manifold from the EGR tube. The temperatures at this end are in the range that will not permit long-term contact between the manifold and the EGR tube. Nevertheless, it is possible to use a plastic fitting along with an elastomeric seal to make the connection. Therefore, there is an opportunity to utilize a quick connect configuration.
Prior art connectors of the type described suffer from requiring a multiplicity of parts, some of which necessitate complex molding with intricate small components which are subject to failure.